Talk of “bloodcurdling screams” and shots in the night took center stage Monday in the first day of testimony in the murder trial of South African amputee track star Oscar Pistorius, who killed his model girlfriend, Reeva Steenkamp, last year.

“Something terrible was happening at that house,” Michelle Burger testified.

“Her shouts, her screams were petrifying,” she said later.

Burger was the only witness Monday in a trial that is expected to last a few weeks. Testimony was scheduled to resume Tuesday morning.

Under questioning by prosecutors, Burger told the court that she heard a woman’s screams and a man yelling for help.

“Just after 3, I woke up from a woman’s terrible screams,” she said. “Then I also heard a man screaming for help. Three times he yelled for help.”